Methods and systems for a ranging protocol

ABSTRACT

Disclosed are methods, systems and devices for obtaining a range between devices based, at least in part, on an exchange of wireless messages. For example, wireless devices may obtain measurements of range based, at least in part, on an exchange fine timing measurement (FTM) messages. In one implementation, a subsequent FTM message transmitted in response to an FTM request message may comprise at least one field indicating a time of transmission of a previous FTM message and a time of receipt of an acknowledgement message transmitted in response to the previous FTM message.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/300,707, entitled “Methods and Systems for a Ranging Protocol,” filedFeb. 26, 2016, which is assigned to the assignee hereof and which isexpressly incorporated herein by reference.

BACKGROUND

Field

Embodiments described herein are directed to obtaining measurements ofsignals acquired from a mobile transmitter.

Information

Satellite positioning systems (SPSs), such as the global positioningsystem (GPS), have enabled navigation services for mobile handsets inoutdoor environments. Likewise, particular techniques for obtainingestimates of positions of mobile device in indoor environments mayenable enhanced location based services in particular indoor venues suchas residential, governmental or commercial venues. For example, a rangebetween a mobile device and a transceiver positioned at fixed locationmay be measured based, at least in part, on a measurement of a roundtrip time (RTT) measured between transmission of a first message from afirst device to a second device and receipt of a second message at thefirst device transmitted in response to the first message.

SUMMARY

Briefly, one particular implementation is directed to a method at aresponding STA comprising: receiving a fine timing measurement (FTM)request message from an initiating STA; and transmitting at least asubsequent FTM message to the initiating STA in response to the FTMrequest message, the subsequent FTM message comprising at least onefield indicating a time of transmission of a previous FTM message and atime of receipt of an acknowledgement message transmitted in response toreceipt of the previous FTM, the at least one field comprising a commonportion indicative of most significant portions of the time oftransmission of the previous FTM message and the time of receipt of theacknowledgement message, a first fractional portion indicative of thetime of transmission of the previous FTM message and a second fractionportion indicative of the time of receipt of the acknowledgementmessage.

Another particular implementation is directed to a responding wirelessstation (STA), comprising: a wireless transceiver; and a processorcoupled to the wireless transceiver, the processor configured to: obtaina fine timing measurement (FTM) request message received at the wirelesstransceiver from an initiating STA; and initiate transmission of atleast a subsequent FTM message through the wireless transceiver to theinitiating STA in response to the FTM request message, the subsequentFTM message comprising at least one field indicating a time oftransmission of a previous FTM message and a time of receipt of anacknowledgment message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe acknowledgement message and the time of transmission of the initialFTM message, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fraction portionindicative of the time of receipt of acknowledgement message.

Another particular implementation is directed to a responding wirelessstation (STA) comprising: means for obtaining a fine timing measurement(FTM) request message received from an initiating STA; and means forinitiating transmission of at least a subsequent FTM message to theinitiating STA in response to the FTM request message, the subsequentFTM message comprising at least one field indicating a time oftransmission of a previous FTM message and a time of receipt of anacknowledgement message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fractional portionindicative of the time of receipt of the acknowledgement message.

Another particular implementation is directed to a non-transitorystorage medium comprising computer readable instructions stored thereonwhich are executable by a processor of a first wireless transceiverdevice to: obtain a fine timing measurement (FTM) request messagereceived at the wireless transceiver from a second wireless transceiverdevice; and initiate transmission of at least a subsequent FTM messageto the second wireless transceiver device in response to the FTM requestmessage, the subsequent FTM message comprising at least one fieldindicating a time of transmission of a previous FTM message and a timeof receipt of an acknowledgement message transmitted in response toreceipt of the previous FTM message, the at least one field comprising acommon portion indicative of most significant portions of the time oftransmission of the previous FTM message and the time of receipt of theacknowledgement message, a first fractional portion indicative of thetime of transmission of the previous FTM message and a second fractionalportion indicative of the time of receipt of the acknowledgementmessage.

As described above, one particular embodiment is directed to a method,at an initiating wireless station (STA), comprising: transmitting a finetiming measurement (FTM) request message to a responding initiating STA;and receiving at least a subsequent FTM message transmitted from theresponding STA in response to the FTM request message, the subsequentFTM message comprising at least one field indicating a time oftransmission of a previous FTM message and a time of receipt of anacknowledgement message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fraction portionindicative of the time of receipt of the acknowledgement message.

As described above, another particular embodiment is directed to aninitiating wireless station (STA), comprising: a wireless transceiver;and a processor coupled to the wireless transceiver, the processorconfigured to: initiate transmission of a fine timing measurement (FTM)request message through the wireless transceiver to a responding STA;and obtain at least subsequent FTM message transmitted by the respondingSTA in response to the FTM request message and received at the wirelesstransceiver to the initiating STA, the subsequent FTM message comprisingat least one field indicating a time of transmission of a previous FTMmessage and a time of receipt of an acknowledgement message transmittedin response to the previous FTM message, the at least one fieldcomprising a common portion indicative of most significant portions ofthe time of transmission of the previous FTM message and the time ofreceipt of the acknowledgement message, a first fractional portionindicative of the time of transmission of the previous FTM message and asecond fraction portion indicative of the time of receipt of theacknowledgement message.

As described above, another particular embodiment is directed to aninitiating wireless station (STA), comprising: means for transmitting afine timing measurement (FTM) request message to a responding initiatingSTA; and means for receiving at least a subsequent FTM messagetransmitted from the responding STA in response to the FTM requestmessage, the subsequent FTM message comprising at least one fieldindicating a time of transmission of the previous FTM message and a timeof receipt of an acknowledgement message transmitted in response toreceipt of the previous FTM message, the at least one field comprising acommon portion indicative of most significant portions of the time oftransmission of the previous FTM message and the time of receipt of theacknowledgement message, a first fractional portion indicative of thetime of transmission of the previous FTM message and a second fractionportion indicative of the time of receipt of the acknowledgementmessage.

As described above, another particular embodiment is directed to anon-transitory storage medium comprising computer readable instructionsstored thereon which are executable by a processor of a first wirelesstransceiver device to: initiate transmission of a fine timingmeasurement (FTM) request message to a responding STA; and obtain atleast a subsequent FTM message transmitted by the responding STA inresponse to the FTM request message to the initiating STA, thesubsequent FTM message comprising at least one field indicating a timeof transmission of a previous FTM message and a time of receipt of anacknowledgement message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fraction portionindicative of the time of receipt of the acknowledgement message.

Another particular embodiment is directed to a method, at a respondingSTA, comprising: receiving a fine timing measurement (FTM) requestmessage from an initiating STA; and transmitting at least an FTM messageto the initiating STA in response to the FTM request message, the FTMmessage comprising at least one field indicating a time of receipt ofthe FTM request message and a time of transmission of the FTM message,the at least one field comprising a common portion indicative of mostsignificant portions of the time of receipt of the FTM request messageand the time of transmission of the FTM message, a first fractionalportion indicative of the time of receipt of the FTM request message anda second fraction portion indicative of the time of transmission of theFTM message.

Another particular implementation is directed to a responding wirelessstation (STA), comprising: a wireless transceiver; and a processorcoupled to the wireless transceiver, the processor configured to: obtaina fine timing measurement (FTM) request message received at the wirelesstransceiver from an initiating STA; and initiate transmission of atleast an FTM message through the wireless transceiver to the initiatingSTA in response to the FTM request message, the FTM message comprisingat least one field indicating a time of receipt of the FTM requestmessage and a time of transmission of the FTM message, the at least onefield comprising a common portion indicative of most significantportions of the time of receipt of the FTM request message and the timeof transmission of the FTM message, a first fractional portionindicative of the time of receipt of the FTM request message and asecond fraction portion indicative of the time of transmission of theFTM message.

Another particular implementation is directed to a responding wirelessstation (STA) comprising: means for obtaining a fine timing measurement(FTM) request message received from an initiating STA; and means forinitiating transmission of at least an initial FTM message to theinitiating STA in response to the FTM request message, the initial FTMmessage comprising at least one field indicating a time of receipt ofthe FTM request message and a time of transmission of the initial FTMmessage, the at least one field comprising a common portion indicativeof most significant portions of the time of receipt of the FTM requestmessage and the time of transmission of the initial FTM message, a firstfractional portion indicative of the time of receipt of the FTM requestmessage and a second fraction portion indicative of the time oftransmission of the initial FTM message.

Another particular implementation is directed to a non-transitorystorage medium comprising computer readable instructions stored thereonwhich are executable by a processor of a first wireless transceiverdevice to: obtain a fine timing measurement (FTM) request messagereceived at the wireless transceiver from a second wireless transceiverdevice; and initiate transmission of at least an FTM to the secondwireless transceiver device in response to the FTM request message, theFTM message comprising at least one field indicating a time of receiptof the FTM request message and a time of transmission of the FTMmessage, the at least one field comprising a common portion indicativeof most significant portions of the time of receipt of the FTM requestmessage and the time of transmission of the FTM message, a firstfractional portion indicative of the time of receipt of the FTM requestmessage and a second fraction portion indicative of the time oftransmission of the FTM message.

Another particular implementation is directed to a method, at aninitiating wireless station (STA), comprising: transmitting a finetiming measurement (FTM) request message to a responding initiating STA;and receiving at least an FTM message transmitted from the respondingSTA in response to the FTM request message, the initial FTM messagecomprising at least one field indicating a time of receipt of the FTMrequest message and a time of transmission of the FTM message, the atleast one field comprising a common portion indicative of mostsignificant portions of the time of receipt of the FTM request messageand the time of transmission of the FTM message, a first fractionalportion indicative of the time of receipt of the FTM request message anda second fraction portion indicative of the time of transmission of theFTM message.

Another particular implementation is directed to an initiating wirelessstation (STA), comprising: a wireless transceiver; and a processorcoupled to the wireless transceiver, the processor configured to:initiate transmission of a fine timing measurement (FTM) request messagethrough the wireless transceiver to a responding STA; and obtain atleast an FTM message transmitted by the responding STA in response tothe FTM request message and received at the wireless transceiver to theinitiating STA, the FTM message comprising at least one field indicatinga time of receipt of the FTM request message and a time of transmissionof the FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of receipt of theFTM request message and the time of transmission of the FTM message, afirst fractional portion indicative of the time of receipt of the FTMrequest message and a second fraction portion indicative of the time oftransmission of the FTM message.

Another particular implementation is directed to an initiating wirelessstation (STA), comprising: means for transmitting a fine timingmeasurement (FTM) request message to a responding initiating STA; andmeans for receiving at least an FTM message transmitted from theresponding STA in response to the FTM request message, the FTM messagecomprising at least one field indicating a time of receipt of the FTMrequest message and a time of transmission of the FTM message, the atleast one field comprising a common portion indicative of mostsignificant portions of the time of receipt of the FTM request messageand the time of transmission of the FTM message, a first fractionalportion indicative of the time of receipt of the FTM request message anda second fraction portion indicative of the time of transmission of theFTM message.

Another particular implementation is directed to a non-transitorystorage medium comprising computer readable instructions stored thereonwhich are executable by a processor of a first wireless transceiverdevice to: initiate transmission of a fine timing measurement (FTM)request message to a responding STA; and obtain at least an FTM messagetransmitted by the responding STA in response to the FTM request messageto the initiating STA, the initial FTM message comprising at least onefield indicating a time of receipt of the FTM request message and a timeof transmission of the FTM message, the at least one field comprising acommon portion indicative of most significant portions of the time ofreceipt of the FTM request message and the time of transmission of theFTM message, a first fractional portion indicative of the time ofreceipt of the FTM request message and a second fraction portionindicative of the time of transmission of the FTM message.

It should be understood that the aforementioned implementations aremerely example implementations, and that claimed subject matter is notnecessarily limited to any particular aspect of these exampleimplementations.

BRIEF DESCRIPTION OF THE DRAWINGS

Claimed subject matter is particularly pointed out and distinctlyclaimed in the concluding portion of the specification. However, both asto organization and/or method of operation, together with objects,features, and/or advantages thereof, it may best be understood byreference to the following detailed description if read with theaccompanying drawings in which:

FIG. 1 is a system diagram illustrating certain features of a systemcontaining a mobile device, in accordance with an implementation;

FIGS. 2 and 3 are message flow diagrams according to particularembodiments;

FIG. 4 shows fields of a fine timing measurement (FTM) message accordingto an embodiment;

FIGS. 5 and 6 are flow diagrams of processes to exchanges FTM messagesbetween wireless stations according to an embodiment;

FIGS. 7 and 8 are flow diagrams of processes to exchanges FTM messagesbetween wireless stations according to an embodiment;

FIG. 9 is a schematic block diagram illustrating an exemplary device, inaccordance with an implementation; and

FIG. 10 is a schematic block diagram of an example computing system inaccordance with an implementation;

Reference is made in the following detailed description to accompanyingdrawings, which form a part hereof, wherein like numerals may designatelike parts throughout that are corresponding and/or analogous. It willbe appreciated that the figures have not necessarily been drawn toscale, such as for simplicity and/or clarity of illustration. Forexample, dimensions of some aspects may be exaggerated relative toothers. Further, it is to be understood that other embodiments may beutilized. Furthermore, structural and/or other changes may be madewithout departing from claimed subject matter. References throughoutthis specification to “claimed subject matter” refer to subject matterintended to be covered by one or more claims, or any portion thereof,and are not necessarily intended to refer to a complete claim set, to aparticular combination of claim sets (e.g., method claims, apparatusclaims, etc.), or to a particular claim. It should also be noted thatdirections and/or references, for example, such as up, down, top,bottom, and so on, may be used to facilitate discussion of drawings andare not intended to restrict application of claimed subject matter.Therefore, the following detailed description is not to be taken tolimit claimed subject matter and/or equivalents.

DETAILED DESCRIPTION

References throughout this specification to one implementation, animplementation, one embodiment, an embodiment, and/or the like meansthat a particular feature, structure, characteristic, and/or the likedescribed in relation to a particular implementation and/or embodimentis included in at least one implementation and/or embodiment of claimedsubject matter. Thus, appearances of such phrases, for example, invarious places throughout this specification are not necessarilyintended to refer to the same implementation and/or embodiment or to anyone particular implementation and/or embodiment. Furthermore, it is tobe understood that particular features, structures, characteristics,and/or the like described are capable of being combined in various waysin one or more implementations and/or embodiments and, therefore, arewithin intended claim scope. In general, of course, as has always beenthe case for the specification of a patent application, these and otherissues have a potential to vary in a particular context of usage. Inother words, throughout the patent application, particular context ofdescription and/or usage provides helpful guidance regarding reasonableinferences to be drawn; however, likewise, “in this context” in generalwithout further qualification refers to the context of the presentpatent application.

As discussed below, particular message flows may enable effective andefficient measurements of a range in connection with a transmission ofmessages between wireless stations (STAs). In a particular example, aSTA may comprise any one of several types of transceiver devices suchas, for example, a mobile user station (e.g., smartphone, notebookcomputer, tablet computer, etc.) or wireless service access device(e.g., wireless local area network (WLAN) access point, personal areanetwork (PAN) or femto cell). Particular message flows and fields inmessage frames may enable obtaining round-trip time (RTT) or time offlight (TOF) measurements with sufficient accuracy for measuring a rangebetween the wireless STAs using fewer messages, for example. Such ameasured range may be used in any one of several applications includingpositioning operations, for example.

As discussed below, a first STA may transmit a fine timing measurementrequest message to a second STA to initiate a process for an exchange ofmessages or frames enabling the first STA to obtain an RTT or TOFmeasurement. In a particular implementation, subsequent to computationof an RTT or TOF measurement, the first STA may transmit one or moremessages to the second STA comprising a computed range, TOF or RTTmeasurement or other parameter indicative of range. It should beunderstood that this is merely an example implementation and thatclaimed subject matter is not limited in this respect.

Transmissions of messages between STAs for the measurement of RTTtypically occurs in addition to other message traffic supporting otherapplications such as voice, video, HTTP, data, just to provide a fewexamples. Accordingly, in dense operating environments, messagingbetween STAs for the measurement of RTT may increase congestion andcontention for wireless link resources. In particular implementationsdiscussed below, particular positioning techniques may be supported bymeasuring a TOF for the transmission of a message between STAs usingfewer messages than typical techniques used for measuring RTT. Accordingto an embodiment, TOF may be measured for individual messages in a“burst” of messages transmitted close in a sequence. Combining multipleTOF measurements from a burst of received messages may enable reductionin measurement errors, for example.

According to an embodiment, as shown in FIG. 1, mobiles device 100 a or100 b may transmit radio signals to, and receive radio signals from, awireless communication network. In one example, a mobile device 100 maycommunicate with a communication network by transmitting wirelesssignals to, or receiving wireless signals from, a local transceiver 115over a wireless communication link 125.

In a particular implementation, a local transceiver 115 may bepositioned in an indoor environment. A local transceiver 115 may provideaccess to a wireless local area network (WLAN, e.g., IEEE Std. 802.11network) or wireless personal area network (WPAN, e.g., Bluetoothnetwork). In another example implementation, a local transceiver 115 maycomprise a femto cell transceiver capable of facilitating communicationon wireless communication link 125 according to a cellular communicationprotocol. Of course it should be understood that these are merelyexamples of networks that may communicate with a mobile device over awireless link, and claimed subject matter is not limited in thisrespect.

In a particular implementation, local transceiver 115 a or 115 b maycommunicate with servers 140, 150 and/or 155 over a network 130 throughlinks 145. Here, network 130 may comprise any combination of wired orwireless links. In a particular implementation, network 130 may compriseInternet Protocol (IP) infrastructure capable of facilitatingcommunication between a mobile device 100 and servers 140, 150 or 155through a local transceiver 115. In another implementation, network 130may comprise wired or wireless communication network infrastructure tofacilitate mobile cellular communication with mobile device 100.

In a particular implementation, mobile device 100 may be capable ofcomputing a position fix based, at least in part, on signals acquiredfrom local transmitters (e.g., WLAN access points positioned at knownlocations). For example, mobile devices may obtain a position fix bymeasuring ranges to three or more indoor terrestrial wireless accesspoints which are positioned at known locations. Such ranges may bemeasured, for example, by obtaining a MAC ID address from signalsreceived from such access points and obtaining range measurements to theaccess points by measuring one or more characteristics of signalsreceived from such access points such as, for example, received signalstrength (RSSI) or RTT.

In particular implementations, a mobile device 100 or a localtransceiver 115 may receive positioning assistance data for indoorpositioning operations from servers 140, 150 or 155. For example, suchpositioning assistance data may include locations and identities oftransmitters positioned at known locations to enable measuring ranges tothese transmitters based, at least in part, on a measured RSSI and/orRTT, for example.

In a particular implementation, particular messages flows betweenwireless STAs may be implemented for obtaining a measurement of RTT froman exchange of messages between the STAs for use in positioningoperations as discussed above. In particular implementations, asdescribed below, any STA may comprise a mobile device (e.g., mobiledevice 100) or a stationary transceiver (e.g., IEEE std. 802.11 accesspoint, stationary Bluetooth device, local transceiver 115, etc.). Assuch, an exchange of messages between wireless STAs may comprise anexchange of messages between a mobile device and a stationarytransceiver (e.g., between a mobile device 100 and local transceiver 115over a wireless link 125), between two peer mobile devices (e.g.,between mobile devices 100 a and 100 b over wireless link 159), orbetween two stationary transceivers (e.g., between local transceiver 115a and local transceiver 115 b over wireless link 179), just to provide afew examples. In particular implementations, various techniquesdescribed herein may incorporate some, but not necessarily all, aspectsor features of IEEE P802.11-REVmc™/D6.0 Draft Standard 802.11 forInformation technology—Telecommunications and information exchangebetween systems, Local and metropolitan area networks—Specificrequirements Part 11: Wireless LAN Medium Access Control (MAC) andPhysical Layer (PHY), June 2016, (hereinafter “IEEE std. 802.11”).Indeed, it should be understood that some features described herein arenot shown, described or taught in the IEEE std. 802.11.

FIG. 2 is a diagram illustrating a message flow between wirelessstations STAs including a “responding” STA and an “initiating” STAaccording to an embodiment. In this context, a responding STA orinitiating STA may comprise any one of several transceiver devicesincluding a mobile device (e.g., mobile device 100) or stationary accesstransceiver device (e.g., local transceiver 115). It should beunderstood, however, that these are merely examples of an initiating STAor a responding STA, and claimed subject matter is not limited in thisrespect. An initiating STA may obtain or compute one or moremeasurements of RTT based, at least in part, on timing of messages orframes transmitted between the initiating STA and a responding STA. Asused herein, the terms “message” and “frame” are used interchangeably.The initiating STA may transmit a fine timing measurement requestmessage or frame (“Request”) 202 to the responding STA and receive afine timing request message acknowledgement message or frame (“Ack”) 204transmitted in response. In a particular implementation, while notlimiting claimed subject matter in this respect, contents of such a finetiming measurement request message 202 may be as shown in the IEEE std.802.11. In particular implementations, such an Ack frame 204 may merelyprovide an indication of receipt of a previously transmitted message.The initiating STA may then obtain or compute an RTT measurement based,at least in part, on time stamp values (t1, t4) provided in fine timingmeasurement messages or frames (“M”) 206 received from the respondingSTA (and transmitted in response to receipt of a fine timing measurementrequest message). In a particular implementation, as shown in themessage flow diagram, a sequence of multiple exchanges of alternatingfine timing measurement messages 206 followed by fine timing measurementacknowledgement messages 208 may create additional time stamp values(t1, t2, t3 and t4).

In this context, an “FTM message” as referred to herein means a messagetransmitted from a first device to a second device comprising at leastone field having a precise indication of a time of transmission from thefirst device. As discussed above, such a field indicating at time oftransmission of the FTM message may permit the recipient second deviceto compute one or more parameters indicative of a range between thefirst and second devices. An FTM message transmitted by the first devicemay be initiated by receipt of an FTM request message transmitted by thesecond device. In this context, an “FTM request message” as referred toherein means a message transmitted to the first device requestingtransmission of one or more FTM messages to the second device.

According to an embodiment, a fine timing measurement request (FTMR)message transmitted by an initiating STA may include fields, parameters,etc. characterizing a desired exchange of messages with a responding STAto provide fine timing measurements to the initiating STA enabling theinitiating STA to compute an RTT measurement. In response to receipt ofa FTM request message, a responding STA may transmit to the initiatingSTA one or more fine timing measurement (FTM) messages includingmeasurements or parameters enabling the initiating STA to compute RTT orother parameters indicative of range.

In a particular implementation, while not limiting claimed subjectmatter in this respect, contents of such a fine timing measurementmessage or frame may be as shown in the IEEE std. 802.11. In one exampleimplementation, an initiating STA may compute an RTT measurement as(t4−t1)−(t3−t2), where t2 and t3 are the time of receipt of a previousfine timing measurement message or frame and transmission of a precedingacknowledgement message or frame, respectively. The initiating STA mayreceive fine timing measurement frames in a burst to obtain acorresponding number of RTT measurements which may be combined forsuppression of unbiased measurement noise in computing a range betweenthe initiating and responding STAs.

According to an embodiment, a TOF of a message wirelessly transmittedfrom a transmitting device and acquired at a receiving device may bemeasured if the transmitted message includes a time stamp valueindicating a transmission time. In a particular implementation, thetransmitted message may comprise fields (e.g., preamble, header andpayload) containing encoded symbols that are detectable at the receivingdevice. To acquire the transmitted message and determine a time ofarrival, the receiving device may detect or decode a particular symbolor symbols in a sequence of symbols being transmitted by the message. Ifthe particular symbol is referenced to the time stamp value alsoincluded in the transmitted message, the receiving device may measureTOF=RTT/2 based on a different between the time stamp value and aninstance that the particular symbol is decoded or detected.

FIG. 3 is a message flow diagram illustrating an exchange of FTMmessages for computing a range between an initiating STA and aresponding STA according to an embodiment. The initiating STA maytransmit an initial FTM request message 302 including parametersrequesting that the responding STA transmit one or more bursts of FTMmessages. The responding STA may respond to initial FTM request message302 with an initial FTM message 304 including parameters indicating, forexample, timing of bursts of FTM messages that are scheduled to follow.To initiate transmission of a scheduled burst, prior to commencement ofthe burst of FTM messages the initiating STA may transmit an FTM requestmessage 306 including a trigger parameter.

In providing a mechanism for computing range based on an exchange of FTMmessages, IEEE std. 802.11 specifies that the responding STA providevalues indicative of a state of partial timing synchronization function(PTSF) may be used to indicate a time of a start of a burst of FTMmessages to be transmitted by the responding STA. For example, a stateof PTSF may indicate a time after which the responding STA may expect toreceive an FTM request message 306 triggering transmission of FTMmessages. A state of PTSF may comprise 16 bits, which is a portion of atiming synchronization function (TSF) (in 1024 μs units). In animplementation, PTSF timer state may be provided in FTM message 304 asan optional information element (IE) part of the Fine Timing MeasurementParameter information element (FTM Param IE). Based on a PTSF state inFTM message 304, the initiating STA may calculate a TSF state at which aburst instance is to begin and, accordingly, a time to send an FTMmessage 306 with parameters for triggering a burst of FTM messages. Inan embodiment, the initiating STA may synchronize with the TSF timer ofthe responding STA to be able to interpret the PTSF timer (in an FTMmessage 304). In an implementation, synchronization may occur based onan optional Information element (TSF Sync IE) that is part of an initialFTM message or frame of a burst of FTM messages. In a particularimplementation, a state of a PTSF timing in a TSF Sync IE of an initialFTM message 304 may comprise a state of a TSF timer of the respondingSTA at an instance that initial FTM request message 302 is received atthe responding STA. Similarly, a field TSF Sync IE in an FTM message 308may contain the least four significant bytes of a state of a TSF timermaintained at the responding STA at an instance that a preceding FTMrequest message 306 is received.

Disadvantageously, this particular approach to providing a state of PTSFin an initial FTM message of a burst may be longer than other FTMmessages as it includes the field “TSF Sync IE.” Additionally,opportunities to synchronize the initiating STA with the TSF state atthe responding STA's TSF timer may be limited to once per burst.According to an embodiment, parameters in an FTM message from aresponding STA may enable an initiating STA to synchronize to a TSFstate at the responding STA on any particular FTM message without use ofthe optional TSF Synch IE in an FTM message. This may enable powersaving by the initiating STA and a reduction in wireless medium usage.

As shown in FIG. 4, a “TSF Sync IE” field may contain the four leastsignificant bytes of the state of the TSF at the instance that an FTMmessage is transmitted from a responding STA. According to anembodiment, a responding STA may include parameters indicative of astate of the TSF in an FTM message without use of the “TSF Sync IE”field. In a particular implementation, as illustrated in FIG. 4 fieldsTOD and TOA (comprising twelve bytes or 96 bits collectively), may bereorganized/reallocated to include an “X” number of bits for asynchronization portion indicating a state of a TSF of a responding STAat an instance that an FTM message is transmitted and an instance thatan acknowledgement message is received (e.g., an acknowledgment messagethat is transmitted by an initiating STA in response to receipt of theFTM message). A “Y” number of bits may be used to indicate fractionalportions of a state of the TSF at the instance that the FTM message istransmitted and the instance that the acknowledgement message isreceived. For example, a first “Y” number of bits may express a firstfractional portion indicating a time of departure (TOD) (e.g., instanceof transmission) of the FTM message from a responding STA and a second“Y” number of bits may express a second fractional portion indicating atime of arrival (TOA) (e.g., instance of receipt) of the acknowledgementmessage at the responding STA.

In an alternative embodiment, fields TOD and TOA as shown in FIG. 4(comprising twelve bytes or 96 bits collectively), may bereorganized/reallocated to include an “X” number of bits for asynchronization portion indicating a state of a TSF of a responding STAat an instance that an FTM request message is received, “Y” number ofbits for a first fractional portion indicating a time of arrival (TOA)of the FTM request message and “Y” number of bits for a secondfractional portion indicating a time of transmission (TOD) of the FTMmessage.

Maintaining within a total allocation of 96 bits for the combination offields TOA and TOD, values for “X” and “Y” may be subject to theconstraint of X+2*Y=96. In a particular implementation, a particularallocation of X and Y may enable representation of TOD and TOA in termsof a state of the TSF at the responding STA while permitting picosecondresolution for TOA and TOD. In particular implementations, potentialvalues for “X” and “Y” may be selected from among the following:

X=8, Y=44 [allows for TOA and TOD to be different in 2⁴⁴*1.0 ps=17.6seconds];   1)

X=16, Y=40 [allows for TOA and TOD to be different in 2⁴⁰*1.0 ps=1.1seconds]  2)

X=24, Y=36 [allows for TOA and TOD to be different in 2³⁶*1.0 ps=68.7ms]  3)

X=32, Y=32 [allows for TOA and TOD to be different in 2³²*1.0 ps=4.0ms]  4)

X=40, Y=28 [allows for TOA and TOD to be different in 2²⁸*1.0 ps=268.0μs].   5)

In the above representation, units of picoseconds may be employed. In aparticular example, use of 20 fractional bits for “Y” may be consistentwith a definition of TSF state. Remaining bits as a fractional part mayenable a resolution of 0.95 ps. In a particular example, X=24 bits [toexpress bits 8-31 of the TSF state] and Y=36 bits. In this particularcase, an LSB may represent 2⁻³⁶*256.0 μs=0.0037 ps, which is more thansufficient to implement 1.0 picosecond resolution. In another example,setting X=24 [to express bits 8-31 of the TSF state] and Y=28 providesLSBs that represent 2⁻²⁸*256.0 us=0.9537 ps. With this particularimplementation, 1.2 hours of TSF state may be represented whilemaintaining 16 bits as reserved bits. In this case, only 24+28+28=80bits may be used to express the aforementioned synchronous andfractional portions.

According to an embodiment, and in particular scenarios, between thetimestamp values of TOD and TOA expressed relative to a state of theTSF, a value for TOD may “wraparound” in that state of the TSF reaches amaximum and begins incrementing from zero between the events for TOA andTOD. In one implementation, this would mean X is no longer the commonpart between TOD and TOA due to the wraparound. Such a wraparound may bedetected if TOA is much less than TOD. To differentiate between thesetwo cases, a reserved bit in an FTM frame format to indicate wraparoundof the common part between TOD and TOA. In another embodiment, a mostsignificant bit of synchronization portion “X” may be treated as a“wrap-around” bit. The MSB may be set to zero if there is no wraparoundof the common part between TOD and TOA and set to one of there is awraparound condition. As per this embodiment, the MSB of X may be usedto signal the wraparound.

Using bits 8-31 of TSF as X enables 16 bits of savings for every FTM.Using one bit to signal rollover results in considerable savings of 15bits. Implementations discussed above may enable reduction of sevenbytes of the FTM frame length for the first FTM of each burst. This mayenable medium usage savings and power savings. Since an FTM message maynow contain the PTSF of a responding STA, there may be greateropportunity for the initiating STA to synchronize itself with theresponding STA. This is because the synchronization may be performed forevery FTM frame based on the PTSF of a responding STA in the FTM frames.Additionally, an initiating STA may more easily detect whether FTMs arebeing “snooped or misrepresented” by a rogue responding STA. Here, itmay be inferred that an FTM frame having a PTSF that deviatessignificantly from an expected value (e.g., a PTSF value of a previouslyreceived FTM frame). This ability to detect spoofed or unauthentic FTMframes may enable establishment of a trust/validity framework for valuesexpressing TOD and TOA in FTM messages. Implementations discussed hereinmay enable preventing a rogue responding STA from inserting any randomvalues for t1 (time of transmission of a previous FTM message) and t4(time of receipt of an acknowledgement message transmitted in responseto the previous FTM message) in an FTM message and cause the initiatingSTA to unknowingly compute invalid/incorrect RTT. Additionally, theinitiating STA may be synchronized with the responding STA's TSF clock.Since t1, t2 (time of receipt of a previous FTM message), t3(transmission of an acknowledgement message or frame transmitted inresponse to the previous FTM message or frame) and t4 are now beingderived from the same clock, any discrepancy in t1, t4 can be easilydetected by the initiating STA. While a rogue responding STA may besynchronized with an authentic responding STA, such synchronization maybe complicated and difficult unless the rogue responder is exchangingFTM messages with the authentic responding STA (e.g., to “sync” rogueresponding STA's clock with the clock of the authentic responding STA).

FIGS. 5 and 6 are flow diagrams of processes to exchange FTM messagesbetween wireless stations according to an embodiment. In particular,FIG. 5 shows actions that may be performed at an initiating STA and FIG.6 shows actions that may be performed at a responding STA. Block 502 maycomprise transmitting an initial FTM request message (e.g., initial FTMrequest message 302) which may be received at a responding STA at block602. Block 604 may comprise transmitting an initial FTM message (e.g.,initial FTM message 304) in response to the initial FTM request messagetransmitted at block 502. The initial FTM message transmitted at block604 may comprise, for example, at least one field indicating a time ofreceipt of the FTM request message received at block 602 and a time oftransmission of the initial FTM message at block 604. The at least onefield in the initial FTM message transmitted at block 604 may comprise acommon portion indicative of most significant portions of the time ofreceipt of the FTM request message at block 602. This common portion mayinclude, for example, synchronization portion “X” shown in FIG. 4. Theat least one field in the initial FTM message transmitted at block 604may also comprise a first fractional portion indicative of the time ofreceipt of the FTM message at block 602 (e.g., portion “Y (TOAfractional)” shown in FIG. 4) and a second fractional portion indicativeof a time of transmission of the initial FTM message transmitted atblock 604 (e.g., portion “Y (TOD fractional”) shown in FIG. 4). Block504 may receive the initial FTM message transmitted at block 604. Aninitiating STA may use the at least one field indicating the time ofreceipt of the FTM request message and the time of transmission of theinitial FTM message in the initial FTM messages received at block 504to, among other things, compute one or more parameters indicative of arange between the initiating STA and another device.

FIGS. 7 and 8 are flow diagrams of processes to exchange FTM messagesbetween wireless stations according to an embodiment. In particular,FIG. 7 shows actions that may be performed at an initiating STA and FIG.8 shows actions that may be performed at a responding STA. Block 702 maycomprise transmitting a FTM request message (e.g., initial FTM requestmessage 302 or FTM request message 306) which may be received at aresponding STA at block 802. Block 804 may comprise transmitting asubsequent FTM message (e.g., FTM message 312) in response to the FTMrequest message transmitted at block 702. The FTM message transmitted atblock 804 may comprise, for example, at least one field indicating atime of transmission of a previous FTM message (e.g., FTM message 308)and a time of receipt of an acknowledgement message transmitted inresponse to receipt of the previous FTM message (e.g., time oftransmission of an acknowledgement message 310 transmitted in responseto receipt of an FTM message 308). The at least one field in thesubsequent FTM message transmitted at block 804 may comprise a commonportion indicative of most significant portions of the time oftransmission of the previous FTM message. This common portion mayinclude, for example, synchronization portion “X” shown in FIG. 4. Theat least one field in the subsequent FTM message transmitted at block804 may also comprise a first fractional portion indicative of the timeof transmission of the previous FTM message (e.g., portion “Y (TODfractional)” shown in FIG. 4) and a second fractional portion indicativeof a time of receipt of the acknowledgement message transmitted inresponse to receipt of the previous FTM message (e.g., portion “Y (TOAfractional”) shown in FIG. 4). Block 704 may receive the subsequent FTMmessage transmitted at block 804. An initiating STA may use the at leastone field indicating the time of transmission of the previous FTMmessage and the time of receipt of the acknowledgement messagetransmitted in response to receipt of the previous FTM message receivedat block 704 to, among other things, compute one or more parametersindicative of a range between the initiating STA and another device.

In this context, as referred to herein a “time of receipt” of an FTMrequest message as referred to herein means a numerical representationof an instance relative to a reference time (e.g., a TSF timer) that aparticular condition occurs such as, for example, decoding orrecognition of one or more symbols in a received signal. Also in thiscontext, as referred to herein a “fractional portion of a time ofreceipt” of an FTM message as referred to herein refers to a portion ofa numerical representation of a time of receipt of a signal.

In this context, as referred to herein a “time of transmission” of aninitial FTM message as referred to herein means a numericalrepresentation of an instance relative to a reference time (e.g., a TSFtimer) that at least one action at a device is completed to, forexample, transmit a detectable signal in a transmission medium. Also inthis context, as referred to herein a “fractional portion of a time oftransmission” of an FTM message as referred to herein refers to aportion of a numerical representation of a time of transmission of asignal.

In this context, a “common portion indicative of most significantportions” of a “time of receipt” and “time of transmission” as referredto herein means a most significant portion of a numerical representationof both a time of receipt of a first signal and a time of transmissionof a second signal. Such a most significant portion may include, forexample, a most significant bits portion of both a time of receipt ofthe first signal and a time of transmission of the second signal.

In particular implementations, actions performed at blocks 502, 504,602, 604, 702, 704, 802 and 804 may be performed by any one of severaldifferent structures including, for example, wireless transceiver 1121in combination with general purpose/application processor 1111 and/orDSP(s) 1112 and memory 1140, for example. In an alternativeimplementation, blocks 502, 504, 602, 604, 702, 704, 802 and 804 may beperformed by communication interface 1830 (including any wirelesstransceiver devices (not shown)) in combination with processing unit1820 and memory 1822. It should be understood, however, that theperformed at blocks 502, 504, 602, 604, 702, 704, 902 and 804 may beperformed by different structures, and that claimed subject matter isnot limited in this respect.

Subject matter shown in FIGS. 9 and 10 may comprise features, forexample, of a computing device, in an embodiment. It is further notedthat the term computing device, in general, refers at least to one ormore processors and a memory connected by a communication bus. Likewise,in the context of the present disclosure at least, this is understood torefer to sufficient structure within the meaning of 35 USC §112(f) sothat it is specifically intended that 35 USC §112(f) not be implicatedby use of the term “computing device,” “wireless station,” “wirelesstransceiver device” and/or similar terms; however, if it is determined,for some reason not immediately apparent, that the foregoingunderstanding cannot stand and that 35 USC §112(f) therefore,necessarily is implicated by the use of the term “computing device,”“wireless station,” “wireless transceiver device” and/or similar terms,then, it is intended, pursuant to that statutory section, thatcorresponding structure, material and/or acts for performing one or morefunctions be understood and be interpreted to be described at least inFIGS. 5 and 6 corresponding text of the present disclosure.

FIG. 9 is a schematic diagram of a mobile device according to anembodiment. Mobile device 100 (FIG. 1) may comprise one or more featuresof mobile device 1100 shown in FIG. 9. In certain embodiments, mobiledevice 1100 may also comprise a wireless transceiver 1121 which iscapable of transmitting and receiving wireless signals 1123 via wirelessantenna 1122 over a wireless communication network. Wireless transceiver1121 may be connected to bus 1101 by a wireless transceiver businterface 1120. Wireless transceiver bus interface 1120 may, in someembodiments be at least partially integrated with wireless transceiver1121. Some embodiments may include multiple wireless transceivers 1121and wireless antennas 1122 to enable transmitting and/or receivingsignals according to a corresponding multiple wireless communicationstandards such as, for example, versions of IEEE Std. 802.11, CDMA,WCDMA, LTE, UMTS, GSM, AMPS, Zigbee and Bluetooth, just to name a fewexamples.

Mobile device 1100 may also comprise SPS receiver 1155 capable ofreceiving and acquiring SPS signals 1159 via SPS antenna 1158. SPSreceiver 1155 may also process, in whole or in part, acquired SPSsignals 1159 for estimating a location of mobile device 1000. In someembodiments, general-purpose processor(s) 1111, memory 1140, DSP(s) 1112and/or specialized processors (not shown) may also be utilized toprocess acquired SPS signals, in whole or in part, and/or calculate anestimated location of mobile device 1100, in conjunction with SPSreceiver 1155. Storage of SPS or other signals for use in performingpositioning operations may be performed in memory 1140 or registers (notshown).

Also shown in FIG. 9, mobile device 1100 may comprise digital signalprocessor(s) (DSP(s)) 1112 connected to the bus 1101 by a bus interface1110, general-purpose processor(s) 1111 connected to the bus 1101 by abus interface 1110 and memory 1140. Bus interface 1110 may be integratedwith the DSP(s) 1112, general-purpose processor(s) 1111 and memory 1140.In various embodiments, functions may be performed in response executionof one or more machine-readable instructions stored in memory 1140 suchas on a computer-readable storage medium, such as RAM, ROM, FLASH, ordisc drive, just to name a few example. The one or more instructions maybe executable by general-purpose processor(s) 1111, specializedprocessors, or DSP(s) 1112. Memory 1140 may comprise a non-transitoryprocessor-readable memory and/or a computer-readable memory that storessoftware code (programming code, instructions, etc.) that are executableby processor(s) 1111 and/or DSP(s) 1112 to perform functions describedherein. In a particular implementation, wireless transceiver 1121 maycommunicate with general-purpose processor(s) 1111 and/or DSP(s) 1112through bus 1101 to enable mobile device 1100 to be configured as awireless STA as discussed above. General-purpose processor(s) 1111and/or DSP(s) 1112 may execute instructions to execute one or moreaspects of processes discussed above in connection with FIGS. 2 through8.

In one particular implementation, transmission of an ACK message inresponse to a FTM measurement request message may be performed bywireless transceiver device 1121 without instruction or initiation fromgeneral-purpose processor(s) 1111or DSP(s) 1112.

Also shown in FIG. 9, a user interface 1135 may comprise any one ofseveral devices such as, for example, a speaker, microphone, displaydevice, vibration device, keyboard, touch screen, just to name a fewexamples. In a particular implementation, user interface 1135 may enablea user to interact with one or more applications hosted on mobile device1100. For example, devices of user interface 1135 may store analog ordigital signals on memory 1140 to be further processed by DSP(s) 1112 orgeneral purpose/application processor 1111 in response to action from auser. Similarly, applications hosted on mobile device 1100 may storeanalog or digital signals on memory 1140 to present an output signal toa user. In another implementation, mobile device 1100 may optionallyinclude a dedicated audio input/output (I/O) device 1170 comprising, forexample, a dedicated speaker, microphone, digital to analog circuitry,analog to digital circuitry, amplifiers and/or gain control. It shouldbe understood, however, that this is merely an example of how an audioI/O may be implemented in a mobile device, and that claimed subjectmatter is not limited in this respect. In another implementation, mobiledevice 1100 may comprise touch sensors 1162 responsive to touching orpressure on a keyboard or touch screen device.

Mobile device 1100 may also comprise a dedicated camera device 1164 forcapturing still or moving imagery. Dedicated camera device 1164 maycomprise, for example an imaging sensor (e.g., charge coupled device orCMOS imager), lens, analog to digital circuitry, frame buffers, just toname a few examples. In one implementation, additional processing,conditioning, encoding or compression of signals representing capturedimages may be performed at general purpose/application processor 1111 orDSP(s) 1112. Alternatively, a dedicated video processor 1168 may performconditioning, encoding, compression or manipulation of signalsrepresenting captured images. Additionally, dedicated video processor1168 may decode/decompress stored image data for presentation on adisplay device (not shown) on mobile device 1100.

Mobile device 1100 may also comprise sensors 1160 coupled to bus 1101which may include, for example, inertial sensors and environmentsensors. Inertial sensors of sensors 1160 may comprise, for exampleaccelerometers (e.g., collectively responding to acceleration of mobiledevice 1100 in three dimensions), one or more gyroscopes or one or moremagnetometers (e.g., to support one or more compass applications).Environment sensors of mobile device 1100 may comprise, for example,temperature sensors, barometric pressure sensors, ambient light sensors,camera imagers, microphones, just to name few examples. Sensors 1160 maygenerate analog or digital signals that may be stored in memory 1140 andprocessed by DPS(s) or general purpose/application processor 1111 insupport of one or more applications such as, for example, applicationsdirected to positioning or navigation operations.

In a particular implementation, mobile device 1100 may comprise adedicated modem processor 1166 capable of performing baseband processingof signals received and downconverted at wireless transceiver 1121 orSPS receiver 1155. Similarly, dedicated modem processor 1166 may performbaseband processing of signals to be upconverted for transmission bywireless transceiver 1121. In alternative implementations, instead ofhaving a dedicated modem processor, baseband processing may be performedby a general purpose processor or DSP (e.g., general purpose/applicationprocessor 1111 or DSP(s) 1112). It should be understood, however, thatthese are merely examples of structures that may perform basebandprocessing, and that claimed subject matter is not limited in thisrespect.

FIG. 10 is a schematic diagram illustrating an example system 1800 thatmay include one or more devices configurable to implement techniques orprocesses described above, for example, in connection with FIG. 1.System 1800 may include, for example, a first device 1802, a seconddevice 1804, and a third device 1806, which may be operatively coupledtogether through a wireless communications network. In an aspect, firstdevice 1802 may comprise an access point as shown, for example. Seconddevice 1804 may comprise an access point (e.g., local transceiver 115 orbase station transceiver 110) and third device 1806 may comprise amobile station or mobile device, in an aspect. Also, in an aspect,devices 1802, 1804 and 1802 may be included in a wireless communicationsnetwork may comprise one or more wireless access points, for example.However, claimed subject matter is not limited in scope in theserespects.

First device 1802, second device 1804 and third device 1806, as shown inFIG. 10, may be representative of any device, appliance or machine thatmay be configurable to exchange data over a wireless communicationsnetwork. By way of example but not limitation, any of first device 1802,second device 1804, or third device 1806 may include: one or morecomputing devices or platforms, such as, e.g., a desktop computer, alaptop computer, a workstation, a server device, or the like; one ormore personal computing or communication devices or appliances, such as,e.g., a personal digital assistant, mobile communication device, or thelike; a computing system or associated service provider capability, suchas, e.g., a database or data storage service provider/system, a networkservice provider/system, an Internet or intranet serviceprovider/system, a portal or search engine service provider/system, awireless communication service provider/system; or any combinationthereof. Any of the first, second, and third devices 1802, 1804, and1806, respectively, may comprise one or more of an access point or amobile device in accordance with the examples described herein.

Similarly, a wireless communications network, as shown in FIG. 10, isrepresentative of one or more communication links, processes, orresources configurable to support the exchange of data between at leasttwo of first device 1802, second device 1804, and third device 1806. Byway of example but not limitation, a wireless communications network mayinclude wireless or wired communication links, telephone ortelecommunications systems, data buses or channels, optical fibers,terrestrial or space vehicle resources, local area networks, wide areanetworks, intranets, the Internet, routers or switches, and the like, orany combination thereof. As illustrated, for example, by the dashedlined box illustrated as being partially obscured of third device 1806,there may be additional like devices operatively coupled to wirelesscommunications network 1808.

It is recognized that all or part of the various devices and networksshown in FIG. 8, and the processes and methods as further describedherein, may be implemented using or otherwise including hardware,firmware, software, or any combination thereof.

Thus, by way of example but not limitation, second device 1804 mayinclude at least one processing unit 1820 that is operatively coupled toa memory 1822 through a bus 1828.

Processing unit 1820 is representative of one or more circuitsconfigurable to perform at least a portion of a data computing procedureor process. By way of example but not limitation, processing unit 1820may include one or more processors, controllers, microprocessors,microcontrollers, application specific integrated circuits, digitalsignal processors, programmable logic devices, field programmable gatearrays, and the like, or any combination thereof.

Memory 1822 is representative of any data storage mechanism. Memory 1822may include, for example, a primary memory 1824 or a secondary memory1826. Primary memory 1824 may include, for example, a random accessmemory, read only memory, etc. While illustrated in this example asbeing separate from processing unit 1820, it should be understood thatall or part of primary memory 1824 may be provided within or otherwiseco-located/coupled with processing unit 1820. In a particularimplementation, memory 1822 and processing unit 1820 may be configuredto execute one or more aspects of process discussed above in connectionwith FIGS. 2 through 8.

Secondary memory 1826 may include, for example, the same or similar typeof memory as primary memory or one or more data storage devices orsystems, such as, for example, a disk drive, an optical disc drive, atape drive, a solid state memory drive, etc. In certain implementations,secondary memory 1826 may be operatively receptive of, or otherwiseconfigurable to couple to, a computer-readable medium 1840.Computer-readable medium 1840 may include, for example, anynon-transitory medium that can carry or make accessible data, code orinstructions for one or more of the devices in system 1800.Computer-readable medium 1840 may also be referred to as a storagemedium.

Second device 1804 may include, for example, a communication interface1830 that provides for or otherwise supports the operative coupling ofsecond device 1804 to a wireless communications network at least throughan antenna 1808. By way of example but not limitation, communicationinterface 1830 may include a network interface device or card, a modem,a router, a switch, a transceiver, and the like. In other alternativeimplementations, communication interface 1830 may comprise a wired/LANinterface, wireless LAN interface (e.g., IEEE std. 802.11 wirelessinterface) and/or a wide area network (WAN) air interface. In aparticular implementation, antenna 1808 in combination withcommunication interface 1830 may be used to implement transmission andreception of signals as illustrated in FIGS. 2 through 8.

In one particular implementation, transmission of an ACK message inresponse to a FTM measurement request message may be performed atcommunication interface 1830 without instruction or initiation fromprocessing unit 1830.

Second device 1804 may include, for example, an input/output device1832. Input/output device 1832 is representative of one or more devicesor features that may be configurable to accept or otherwise introducehuman or machine inputs, or one or more devices or features that may beconfigurable to deliver or otherwise provide for human or machineoutputs. By way of example but not limitation, input/output device 1832may include an operatively configured display, speaker, keyboard, mouse,trackball, touch screen, data port, etc.

As described above, one particular embodiment is directed to a method,at an initiating wireless station (STA), comprising: transmitting a finetiming measurement (FTM) request message to a responding initiating STA;and receiving at least a subsequent FTM message transmitted from theresponding STA in response to the FTM request message, the subsequentFTM message comprising at least one field indicating a time oftransmission of a previous FTM message and a time of receipt of anacknowledgement message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fraction portionindicative of the time of receipt of the acknowledgement message. In aparticular implementation, the method further comprises computing atleast one parameter indicative of a range between the initiating STA andthe responding STA based, at least in part, on the at least one fieldindicating the time of transmission of the previous FTM message and thetime of receipt of the acknowledgement message. In another particularimplementation, the first fractional portion comprises a TSF clock stateat the time of transmission of the subsequent FTM message. In anotherparticular implementation, the first and second fractional portionscomprise at least picosecond resolution. In another particularimplementation, the at least one field comprises at least 96 bits. Inanother particular implementation, the common portion comprises at leasta portion of a state of a timing synchronization function (TSF) timer ofthe responding STA at a time of transmission of the subsequent FTMmessage. In another particular implementation, the subsequent FTMmessage comprises at least one field indicating a wrap around conditionbetween receipt of the acknowledgement message and transmission of theprevious FTM message.

As described above, another particular embodiment is directed to aninitiating wireless station (STA), comprising: a wireless transceiver;and a processor coupled to the wireless transceiver, the processorconfigured to: initiate transmission of a fine timing measurement (FTM)request message through the wireless transceiver to a responding STA;and obtain at least subsequent FTM message transmitted by the respondingSTA in response to the FTM request message and received at the wirelesstransceiver to the initiating STA, the subsequent FTM message comprisingat least one field indicating a time of transmission of a previous FTMmessage and a time of receipt of an acknowledgement message transmittedin response to the previous FTM message, the at least one fieldcomprising a common portion indicative of most significant portions ofthe time of transmission of the previous FTM message and the time ofreceipt of the acknowledgement message, a first fractional portionindicative of the time of transmission of the previous FTM message and asecond fraction portion indicative of the time of receipt of theacknowledgement message. In a particular implementation, the processoris further configured to compute at least one parameter indicative of arange between the initiating STA and the responding STA based, at leastin part, on the at least one field indicating the time of transmissionof the previous FTM message and the time of receipt of theacknowledgement message. In another particular implementation, the firstfractional portion comprises a TSF clock state at the time oftransmission of the subsequent FTM message. In another particularimplementation, the first and second fractional portions comprise atleast picosecond resolution. In another particular implementation, theat least one field comprises at least 96 bits. In another particularimplementation, the common portion comprises at least a portion of astate of a timing synchronization function (TSF) timer of the respondingSTA at a time of transmission of the subsequent FTM message. In anotherparticular implementation, the subsequent FTM message comprises at leastone field indicating a wrap around condition between receipt of theacknowledgement message and transmission of the previous FTM message.

As described above, another particular embodiment is directed to aninitiating wireless station (STA), comprising: means for transmitting afine timing measurement (FTM) request message to a responding initiatingSTA; and means for receiving at least a subsequent FTM messagetransmitted from the responding STA in response to the FTM requestmessage, the subsequent FTM message comprising at least one fieldindicating a time of transmission of the previous FTM message and a timeof receipt of an acknowledgement message transmitted in response toreceipt of the previous FTM message, the at least one field comprising acommon portion indicative of most significant portions of the time oftransmission of the previous FTM message and the time of receipt of theacknowledgement message, a first fractional portion indicative of thetime of transmission of the previous FTM message and a second fractionportion indicative of the time of receipt of the acknowledgementmessage. In a particular implementation, the initiating STA furthercomprises means for computing at least one parameter indicative of arange between the initiating STA and the responding STA based, at leastin part, on the at least one field indicating the time of transmissionof the previous FTM message and the time of receipt of theacknowledgement message. In another particular implementation, the firstfractional portion comprises a TSF clock state at the time oftransmission of the subsequent FTM message. In another particularimplementation, the first and second fractional portions comprise atleast picosecond resolution. In another particular implementation, theat least one field comprises at least 96 bits. In another particularimplementation, the common portion comprises at least a portion of astate of a timing synchronization function (TSF) timer of the respondingSTA at a time of transmission of the subsequent FTM message. In anotherparticular implementation, the subsequent FTM message comprises at leastone field indicating a wrap around condition between receipt of theacknowledgement message and transmission of the previous FTM message.

As described above, another particular embodiment is directed to anon-transitory storage medium comprising computer readable instructionsstored thereon which are executable by a processor of a first wirelesstransceiver device to: initiate transmission of a fine timingmeasurement (FTM) request message to a responding STA; and obtain atleast a subsequent FTM message transmitted by the responding STA inresponse to the FTM request message to the initiating STA, thesubsequent FTM message comprising at least one field indicating a timeof transmission of a previous FTM message and a time of receipt of anacknowledgement message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fraction portionindicative of the time of receipt of the acknowledgement message. In aparticular implementation, the instructions are further executable bythe processor to compute at least one parameter indicative of a rangebetween the initiating STA and the responding STA based, at least inpart, on the at least one field indicating the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage. In another particular implementation, the first fractionalportion comprises a TSF clock state at the time of transmission of thesubsequent FTM message. In another particular implementation, the firstand second fractional portions comprise at least picosecond resolution.In another particular implementation, the at least one field comprisesat least 96 bits. In another particular implementation, the commonportion comprises at least a portion of a state of a timingsynchronization function (TSF) timer of the responding STA at a time oftransmission of the subsequent FTM message. In another particularimplementation, the subsequent FTM message comprises at least one fieldindicating a wrap around condition between receipt of theacknowledgement message and transmission of the previous FTM message.

As described above, another particular embodiment is directed to amethod, at a responding STA, comprising: receiving a fine timingmeasurement (FTM) request message from an initiating STA; andtransmitting at least an FTM message to the initiating STA in responseto the FTM request message, the FTM message comprising at least onefield indicating a time of receipt of the FTM request message and a timeof transmission of the FTM message, the at least one field comprising acommon portion indicative of most significant portions of the time ofreceipt of the FTM request message and the time of transmission of theFTM message, a first fractional portion indicative of the time ofreceipt of the FTM request message and a second fraction portionindicative of the time of transmission of the FTM message. In oneparticular implementation, the first fractional portion comprises a TSFclock state at the time of transmission of the initial FTM message. Inanother particular implementation, the first and second fractionalportions comprise at least picosecond resolution. In anotherimplementation, the at least one field comprises at least 96 bits. Inanother implementation, the common portion comprises at least a portionof a state of a timing synchronization function (TSF) timer of theresponding STA at a time of transmission of the FTM message. In anotherparticular implementation, the FTM message comprises at least one fieldindicating a wrap around condition between receipt of the FTM requestmessage and transmission of the FTM message.

As described above, another particular embodiment is directed to aresponding wireless station (STA), comprising: a wireless transceiver;and a processor coupled to the wireless transceiver, the processorconfigured to: obtain a fine timing measurement (FTM) request messagereceived at the wireless transceiver from an initiating STA; andinitiate transmission of at least an FTM message through the wirelesstransceiver to the initiating STA in response to the FTM requestmessage, the FTM message comprising at least one field indicating a timeof receipt of the FTM request message and a time of transmission of theFTM message, the at least one field comprising a common portionindicative of most significant portions of the time of receipt of theFTM request message and the time of transmission of the FTM message, afirst fractional portion indicative of the time of receipt of the FTMrequest message and a second fraction portion indicative of the time oftransmission of the FTM message. In one particular implementation, thefirst fractional portion comprises a TSF clock state at the time oftransmission of the initial FTM message. In another particularimplementation, the first and second fractional portions comprise atleast picosecond resolution. In another implementation, the at least onefield comprises at least 96 bits. In another implementation, the commonportion comprises at least a portion of a state of a timingsynchronization function (TSF) timer of the responding STA at a time oftransmission of the FTM message. In another particular implementation,the FTM message comprises at least one field indicating a wrap aroundcondition between receipt of the FTM request message and transmission ofthe FTM message.

As described above, another particular embodiment is directed to aresponding wireless station (STA) comprising, comprising: means forobtaining a fine timing measurement (FTM) request message received froman initiating STA; and means for initiating transmission of at least aninitial FTM message to the initiating STA in response to the FTM requestmessage, the initial FTM message comprising at least one fieldindicating a time of receipt of the FTM request message and a time oftransmission of the initial FTM message, the at least one fieldcomprising a common portion indicative of most significant portions ofthe time of receipt of the FTM request message and the time oftransmission of the initial FTM message, a first fractional portionindicative of the time of receipt of the FTM request message and asecond fraction portion indicative of the time of transmission of theinitial FTM message. In one particular implementation, the firstfractional portion comprises a TSF clock state at the time oftransmission of the initial FTM message. In another particularimplementation, the first and second fractional portions comprise atleast picosecond resolution. In another implementation, the at least onefield comprises at least 96 bits. In another implementation, the commonportion comprises at least a portion of a state of a timingsynchronization function (TSF) timer of the responding STA at a time oftransmission of the FTM message. In another particular implementation,the FTM message comprises at least one field indicating a wrap aroundcondition between receipt of the FTM request message and transmission ofthe FTM message.

As described above, another particular embodiment is directed to anon-transitory storage medium comprising computer readable instructionsstored thereon which are executable by a processor of a first wirelesstransceiver device to: obtain a fine timing measurement (FTM) requestmessage received at the wireless transceiver from a second wirelesstransceiver device; and initiate transmission of at least an FTM to thesecond wireless transceiver device in response to the FTM requestmessage, the FTM message comprising at least one field indicating a timeof receipt of the FTM request message and a time of transmission of theFTM message, the at least one field comprising a common portionindicative of most significant portions of the time of receipt of theFTM request message and the time of transmission of the FTM message, afirst fractional portion indicative of the time of receipt of the FTMrequest message and a second fraction portion indicative of the time oftransmission of the FTM message. In one particular implementation, thefirst fractional portion comprises a TSF clock state at the time oftransmission of the FTM message. In another particular implementation,the first and second fractional portions comprise at least picosecondresolution. In another implementation, the at least one field comprisesat least 96 bits. In another implementation, the common portioncomprises at least a portion of a state of a timing synchronizationfunction (TSF) timer of the responding STA at a time of transmission ofthe FTM message. In another particular implementation, the FTM messagecomprises at least one field indicating a wrap around condition betweenreceipt of the FTM request message and transmission of the FTM message.

As described above, another particular embodiment is directed to amethod, at an initiating wireless station (STA), comprising:transmitting a fine timing measurement (FTM) request message to aresponding initiating STA; and receiving at least an FTM messagetransmitted from the responding STA in response to the FTM requestmessage, the initial FTM message comprising at least one fieldindicating a time of receipt of the FTM request message and a time oftransmission of the FTM message, the at least one field comprising acommon portion indicative of most significant portions of the time ofreceipt of the FTM request message and the time of transmission of theFTM message, a first fractional portion indicative of the time ofreceipt of the FTM request message and a second fraction portionindicative of the time of transmission of the FTM message. In oneparticular implementation, the first fractional portion comprises a TSFclock state at the time of transmission of the FTM message. In anotherparticular implementation, the first and second fractional portionscomprise at least picosecond resolution. In another implementation, theat least one field comprises at least 96 bits. In anotherimplementation, the common portion comprises at least a portion of astate of a timing synchronization function (TSF) timer of the respondingSTA at a time of transmission of the FTM message. In another particularimplementation, the FTM message comprises at least one field indicatinga wrap around condition between receipt of the FTM request message andtransmission of the FTM message.

As described above, another particular embodiment is directed to aninitiating wireless station (STA), comprising: a wireless transceiver;and a processor coupled to the wireless transceiver, the processorconfigured to: initiate transmission of a fine timing measurement (FTM)request message through the wireless transceiver to a responding STA;and obtain at least an FTM message transmitted by the responding STA inresponse to the FTM request message and received at the wirelesstransceiver to the initiating STA, the FTM message comprising at leastone field indicating a time of receipt of the FTM request message and atime of transmission of the FTM message, the at least one fieldcomprising a common portion indicative of most significant portions ofthe time of receipt of the FTM request message and the time oftransmission of the FTM message, a first fractional portion indicativeof the time of receipt of the FTM request message and a second fractionportion indicative of the time of transmission of the FTM message. Inone particular implementation, the first fractional portion comprises aTSF clock state at the time of transmission of the FTM message. Inanother particular implementation, the first and second fractionalportions comprise at least picosecond resolution. In anotherimplementation, the at least one field comprises at least 96 bits. Inanother implementation, the common portion comprises at least a portionof a state of a timing synchronization function (TSF) timer of theresponding STA at a time of transmission of the FTM message. In anotherparticular implementation, the FTM message comprises at least one fieldindicating a wrap around condition between receipt of the FTM requestmessage and transmission of the FTM message.

As described above, another particular embodiment is directed to aninitiating wireless station (STA), comprising: means for transmitting afine timing measurement (FTM) request message to a responding initiatingSTA; and means for receiving at least an FTM message transmitted fromthe responding STA in response to the FTM request message, the FTMmessage comprising at least one field indicating a time of receipt ofthe FTM request message and a time of transmission of the FTM message,the at least one field comprising a common portion indicative of mostsignificant portions of the time of receipt of the FTM request messageand the time of transmission of the FTM message, a first fractionalportion indicative of the time of receipt of the FTM request message anda second fraction portion indicative of the time of transmission of theFTM message. In one particular implementation, the first fractionalportion comprises a TSF clock state at the time of transmission of theFTM message. In another particular implementation, the first and secondfractional portions comprise at least picosecond resolution. In anotherimplementation, the at least one field comprises at least 96 bits. Inanother implementation, the common portion comprises at least a portionof a state of a timing synchronization function (TSF) timer of theresponding STA at a time of transmission of the FTM message. In anotherparticular implementation, the FTM message comprises at least one fieldindicating a wrap around condition between receipt of the FTM requestmessage and transmission of the FTM message.

As described above, another particular embodiment is directed to anon-transitory storage medium comprising computer readable instructionsstored thereon which are executable by a processor of a first wirelesstransceiver device to: initiate transmission of a fine timingmeasurement (FTM) request message to a responding STA; and obtain atleast an FTM message transmitted by the responding STA in response tothe FTM request message to the initiating STA, the initial FTM messagecomprising at least one field indicating a time of receipt of the FTMrequest message and a time of transmission of the FTM message, the atleast one field comprising a common portion indicative of mostsignificant portions of the time of receipt of the FTM request messageand the time of transmission of the FTM message, a first fractionalportion indicative of the time of receipt of the FTM request message anda second fraction portion indicative of the time of transmission of theFTM message. In one particular implementation, the first fractionalportion comprises a TSF clock state at the time of transmission of theFTM message. In another particular implementation, the first and secondfractional portions comprise at least picosecond resolution. In anotherimplementation, the at least one field comprises at least 96 bits. Inanother implementation, the common portion comprises at least a portionof a state of a timing synchronization function (TSF) timer of theresponding STA at a time of transmission of the FTM message. In anotherparticular implementation, the FTM message comprises at least one fieldindicating a wrap around condition between receipt of the FTM requestmessage and transmission of the FTM message.

As used herein, the term “access point” is meant to include any wirelesscommunication station and/or device used to facilitate communication ina wireless communications system, such as, for example, a wireless localarea network, although the scope of claimed subject matter is notlimited in this respect. In another aspect, an access point may comprisea wireless local area network (WLAN) access point, for example. Such aWLAN may comprise a network compatible and/or compliant with one or moreversions of IEEE standard 802.11 in an aspect, although the scope ofclaimed subject matter is not limited in this respect. A WLAN accesspoint may provide communication between one or more mobile devices and anetwork such as the Internet, for example.

As used herein, the term “mobile device” refers to a device that mayfrom time to time have a position location that changes. The changes inposition location may comprise changes to direction, distance,orientation, etc., as a few examples. In particular examples, a mobiledevice may comprise a cellular telephone, wireless communication device,user equipment, laptop computer, other personal communication system(PCS) device, personal digital assistant (PDA), personal audio device(PAD), portable navigational device, and/or other portable communicationdevices. A mobile device may also comprise a processor and/or computingplatform adapted to perform functions controlled by machine-readableinstructions.

The methodologies described herein may be implemented by various meansdepending upon applications according to particular examples. Forexample, such methodologies may be implemented in hardware, firmware,software, or combinations thereof. In a hardware implementation, forexample, a processing unit may be implemented within one or moreapplication specific integrated circuits (“ASICs”), digital signalprocessors (“DSPs”), digital signal processing devices (“DSPDs”),programmable logic devices (“PLDs”), field programmable gate arrays(“FPGAs”), processors, controllers, micro-controllers, microprocessors,electronic devices, other devices units designed to perform thefunctions described herein, or combinations thereof.

Algorithmic descriptions and/or symbolic representations are examples oftechniques used by those of ordinary skill in the signal processingand/or related arts to convey the substance of their work to othersskilled in the art. An algorithm is here, and generally, is consideredto be a self-consistent sequence of operations and/or similar signalprocessing leading to a desired result. In this context, operationsand/or processing involve physical manipulation of physical quantities.Typically, although not necessarily, such quantities may take the formof electrical and/or magnetic signals and/or states capable of beingstored, transferred, combined, compared, processed or otherwisemanipulated as electronic signals and/or states representing variousforms of content, such as signal measurements, text, images, video,audio, etc. It has proven convenient at times, principally for reasonsof common usage, to refer to such physical signals and/or physicalstates as bits, bytes, values, elements, symbols, characters, terms,numbers, numerals, expressions, messages, fields, identifiers frames,measurements, content and/or the like. It should be understood, however,that all of these and/or similar terms are to be associated withappropriate physical quantities and are merely convenient labels. Unlessspecifically stated otherwise, as apparent from the precedingdiscussion, it is appreciated that throughout this specificationdiscussions utilizing terms such as “processing,” “computing,”“calculating,” “determining”, “establishing”, “obtaining”,“identifying”, “selecting”, “generating”, and/or the like may refer toactions and/or processes of a specific apparatus, such as a specialpurpose computer and/or a similar special purpose computing and/ornetwork device. In the context of this specification, therefore, aspecial purpose computer and/or a similar special purpose computingand/or network device is capable of processing, manipulating and/ortransforming signals and/or states, typically represented as physicalelectronic and/or magnetic quantities within memories, registers, and/orother storage devices, transmission devices, and/or display devices ofthe special purpose computer and/or similar special purpose computingand/or network device. In the context of this particular patentapplication, as mentioned, the term “specific apparatus” may include ageneral purpose computing and/or network device, such as a generalpurpose computer, once it is programmed to perform particular functionspursuant to instructions from program software.

In some circumstances, operation of a memory device, such as a change instate from a binary one to a binary zero or vice-versa, for example, maycomprise a transformation, such as a physical transformation. Withparticular types of memory devices, such a physical transformation maycomprise a physical transformation of an article to a different state orthing. For example, but without limitation, for some types of memorydevices, a change in state may involve an accumulation and/or storage ofcharge or a release of stored charge. Likewise, in other memory devices,a change of state may comprise a physical change, such as atransformation in magnetic orientation and/or a physical change and/ortransformation in molecular structure, such as from crystalline toamorphous or vice-versa. In still other memory devices, a change inphysical state may involve quantum mechanical phenomena, such as,superposition, entanglement, and/or the like, which may involve quantumbits (qubits), for example. The foregoing is not intended to be anexhaustive list of all examples in which a change in state form a binaryone to a binary zero or vice-versa in a memory device may comprise atransformation, such as a physical transformation. Rather, the foregoingis intended as illustrative examples.

Wireless communication techniques described herein may be in connectionwith various wireless communications networks such as a wireless widearea network (“WWAN”), a wireless local area network (“WLAN”), awireless personal area network (WPAN), and so on. In this context, a“wireless communication network” comprises multiple devices or nodescapable of communicating with one another through one or more wirelesscommunication links. As shown in FIG. 1, for example, a wirelesscommunication network may comprise two or more devices from mobiledevices 100 a, 100 b, 115 a and 115 b. The term “network” and “system”may be used interchangeably herein. A WWAN may be a Code DivisionMultiple Access (“CDMA”) network, a Time Division Multiple Access(“TDMA”) network, a Frequency Division Multiple Access (“FDMA”) network,an Orthogonal Frequency Division Multiple Access (“OFDMA”) network, aSingle-Carrier Frequency Division Multiple Access (“SC-FDMA”) network,or any combination of the above networks, and so on. A CDMA network mayimplement one or more radio access technologies (“RATs”) such ascdma2000, Wideband-CDMA (“W-CDMA”), to name just a few radiotechnologies. Here, cdma2000 may include technologies implementedaccording to IS-95, IS-2000, and IS-856 standards. A TDMA network mayimplement Global System for Mobile Communications (“GSM”), DigitalAdvanced Mobile Phone System (“D-AMPS”), or some other RAT. GSM andW-CDMA are described in documents from a consortium named “3rdGeneration Partnership Project” (“3GPP”). Cdma2000 is described indocuments from a consortium named “3rd Generation Partnership Project 2”(“3GPP2”). 3GPP and 3GPP2 documents are publicly available. 4G Long TermEvolution (“LTE”) communications networks may also be implemented inaccordance with claimed subject matter, in an aspect. A WLAN maycomprise an IEEE 802.11x network, and a WPAN may comprise a Bluetoothnetwork, an IEEE 802.15x, for example. Wireless communicationimplementations described herein may also be used in connection with anycombination of WWAN, WLAN or WPAN.

In another aspect, as previously mentioned, a wireless transmitter oraccess point may comprise a femtocell, utilized to extend cellulartelephone service into a business or home. In such an implementation,one or more mobile devices may communicate with a femtocell via a codedivision multiple access (“CDMA”) cellular communication protocol, forexample, and the femtocell may provide the mobile device access to alarger cellular telecommunication network by way of another broadbandnetwork such as the Internet.

Techniques described herein may be used with an SPS that includes anyone of several GNSS and/or combinations of GNSS. Furthermore, suchtechniques may be used with positioning systems that utilize terrestrialtransmitters acting as “pseudolites”, or a combination of SVs and suchterrestrial transmitters. Terrestrial transmitters may, for example,include ground-based transmitters that broadcast a PN code or otherranging code (e.g., similar to a GPS or CDMA cellular signal). Such atransmitter may be assigned a unique PN code so as to permitidentification by a remote receiver. Terrestrial transmitters may beuseful, for example, to augment an SPS in situations where SPS signalsfrom an orbiting SV might be unavailable, such as in tunnels, mines,buildings, urban canyons or other enclosed areas. Another implementationof pseudolites is known as radio-beacons. The term “SV”, as used herein,is intended to include terrestrial transmitters acting as pseudolites,equivalents of pseudolites, and possibly others. The terms “SPS signals”and/or “SV signals”, as used herein, is intended to include SPS-likesignals from terrestrial transmitters, including terrestrialtransmitters acting as pseudolites or equivalents of pseudolites.

Likewise, in this context, the terms “coupled”, “connected,” and/orsimilar terms are used generically. It should be understood that theseterms are not intended as synonyms. Rather, “connected” is usedgenerically to indicate that two or more components, for example, are indirect physical, including electrical, contact; while, “coupled” is usedgenerically to mean that two or more components are potentially indirect physical, including electrical, contact; however, “coupled” isalso used generically to also mean that two or more components are notnecessarily in direct contact, but nonetheless are able to co-operateand/or interact. The term coupled is also understood generically to meanindirectly connected, for example, in an appropriate context.

The terms, “and”, “or”, “and/or” and/or similar terms, as used herein,include a variety of meanings that also are expected to depend at leastin part upon the particular context in which such terms are used.Typically, “or” if used to associate a list, such as A, B or C, isintended to mean A, B, and C, here used in the inclusive sense, as wellas A, B or C, here used in the exclusive sense. In addition, the term“one or more” and/or similar terms is used to describe any feature,structure, and/or characteristic in the singular and/or is also used todescribe a plurality and/or some other combination of features,structures and/or characteristics. Likewise, the term “based on” and/orsimilar terms are understood as not necessarily intending to convey anexclusive set of factors, but to allow for existence of additionalfactors not necessarily expressly described. Of course, for all of theforegoing, particular context of description and/or usage provideshelpful guidance regarding inferences to be drawn. It should be notedthat the following description merely provides one or more illustrativeexamples and claimed subject matter is not limited to these one or moreexamples; however, again, particular context of description and/or usageprovides helpful guidance regarding inferences to be drawn.

In this context, the term network device refers to any device capable ofcommunicating via and/or as part of a network and may comprise acomputing device. While network devices may be capable of sending and/orreceiving signals (e.g., signal packets and/or frames), such as via awired and/or wireless network, they may also be capable of performingarithmetic and/or logic operations, processing and/or storing signals,such as in memory as physical memory states, and/or may, for example,operate as a server in various embodiments. Network devices capable ofoperating as a server, or otherwise, may include, as examples, dedicatedrack-mounted servers, desktop computers, laptop computers, set topboxes, tablets, netbooks, smart phones, wearable devices, integrateddevices combining two or more features of the foregoing devices, thelike or any combination thereof. Signal packets and/or frames, forexample, may be exchanged, such as between a server and a client deviceand/or other types of network devices, including between wirelessdevices coupled via a wireless network, for example. It is noted thatthe terms, server, server device, server computing device, servercomputing platform and/or similar terms are used interchangeably.Similarly, the terms client, client device, client computing device,client computing platform and/or similar terms are also usedinterchangeably. While in some instances, for ease of description, theseterms may be used in the singular, such as by referring to a “clientdevice” or a “server device,” the description is intended to encompassone or more client devices and/or one or more server devices, asappropriate. Along similar lines, references to a “database” areunderstood to mean, one or more databases and/or portions thereof, asappropriate.

It should be understood that for ease of description a network device(also referred to as a networking device) may be embodied and/ordescribed in terms of a computing device. However, it should further beunderstood that this description should in no way be construed thatclaimed subject matter is limited to one embodiment, such as a computingdevice and/or a network device, and, instead, may be embodied as avariety of devices or combinations thereof, including, for example, oneor more illustrative examples. References throughout this specificationto one implementation, an implementation, one embodiment, an embodimentand/or the like means that a particular feature, structure, and/orcharacteristic described in connection with a particular implementationand/or embodiment is included in at least one implementation and/orembodiment of claimed subject matter. Thus, appearances of such phrases,for example, in various places throughout this specification are notnecessarily intended to refer to the same implementation or to any oneparticular implementation described. Furthermore, it is to be understoodthat particular features, structures, and/or characteristics describedare capable of being combined in various ways in one or moreimplementations and, therefore, are within intended claim scope, forexample. In general, of course, these and other issues vary withcontext. Therefore, particular context of description and/or usageprovides helpful guidance regarding inferences to be drawn. While therehas been illustrated and described what are presently considered to beexample features, it will be understood by those skilled in the art thatvarious other modifications may be made, and equivalents may besubstituted, without departing from claimed subject matter.Additionally, many modifications may be made to adapt a particularsituation to the teachings of claimed subject matter without departingfrom the central concept described herein. Therefore, it is intendedthat claimed subject matter not be limited to the particular examplesdisclosed, but that such claimed subject matter may also include allaspects falling within the scope of the appended claims, and equivalentsthereof.

What is claimed is:
 1. A method, at a responding STA, comprising:receiving a fine timing measurement (FTM) request message from aninitiating STA; and transmitting at least a subsequent FTM message tothe initiating STA in response to the FTM request message, thesubsequent FTM message comprising at least one field indicating a timeof transmission of a previous FTM message and a time of receipt of anacknowledgement message transmitted in response to receipt of theprevious FTM, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fraction portionindicative of the time of receipt of the acknowledgement message.
 2. Themethod of claim 1, wherein the first fractional portion comprises a TSFclock state at the time of transmission of the subsequent FTM message.3. The method of claim 1, wherein the first and second fractionalportions comprise at least picosecond resolution.
 4. The method of claim3, wherein the at least one field comprises at least 96 bits.
 5. Themethod of claim 1, wherein the common portion comprises at least aportion of a state of a timing synchronization function (TSF) timer ofthe responding STA at a time of transmission of the subsequent FTMmessage.
 6. The method of claim 1, wherein the subsequent FTM messagecomprises at least one field indicating a wrap around condition betweenreceipt of the acknowledgement message e and transmission of theprevious FTM message.
 7. A responding wireless station (STA),comprising: a wireless transceiver; and a processor coupled to thewireless transceiver, the processor configured to: obtain a fine timingmeasurement (FTM) request message received at the wireless transceiverfrom an initiating STA; and initiate transmission of at least asubsequent FTM message through the wireless transceiver to theinitiating STA in response to the FTM request message, the subsequentFTM message comprising at least one field indicating a time oftransmission of a previous FTM message and a time of receipt of anacknowledgment message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe acknowledgement message and the time of transmission of the initialFTM message, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fraction portionindicative of the time of receipt of acknowledgement message.
 8. Theresponding STA of claim 7, wherein the first portion comprises a TSFclock state at the time of transmission of the subsequent FTM message.9. The responding STA of claim 7, wherein the first and secondfractional portions comprise at least picosecond resolution.
 10. Theresponding STA of claim 9, wherein the at least one field comprises atleast 96 bits.
 11. The responding STA of claim 7, wherein the commonportion comprises at least a portion of a state a timing synchronizationfunction (TSF) timer of the responding STA at a time of transmission ofthe subsequent FTM message.
 12. The responding STA of claim 7, whereinthe subsequent FTM message comprises at least one field indicating awrap around condition between receipt of the acknowledgement message andtransmission of the previous FTM message.
 13. A responding wirelessstation (STA) comprising, comprising: means for obtaining a fine timingmeasurement (FTM) request message received from an initiating STA; andmeans for initiating transmission of at least a subsequent FTM messageto the initiating STA in response to the FTM request message, thesubsequent FTM message comprising at least one field indicating a timeof transmission of a previous FTM message and a time of receipt of anacknowledgement message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fractional portionindicative of the time of receipt of the acknowledgement message. 14.The responding STA of claim 13, wherein the first portion comprises aTSF clock state at the time of transmission of the subsequent FTMmessage.
 15. The responding STA of claim 13, wherein the first andsecond fractional portions comprise at least picosecond resolution. 16.The responding STA of claim 15, wherein the at least one field comprisesat least 96 bits.
 17. The responding STA of claim 13, wherein the commonportion comprises at least a portion of a state a timing synchronizationfunction (TSF) timer of the responding STA at a time of transmission ofthe subsequent FTM message.
 18. The responding STA of claim 13, whereinthe subsequent FTM message comprises at least one field indicating awrap around condition between transmission of the previous FTM messageand receipt of the acknowledgement message.
 19. A non-transitory storagemedium comprising computer readable instructions stored thereon whichare executable by a processor of a first wireless transceiver device to:obtain a fine timing measurement (FTM) request message received at thewireless transceiver from a second wireless transceiver device; andinitiate transmission of at least a subsequent FTM message to the secondwireless transceiver device in response to the FTM request message, thesubsequent FTM message comprising at least one field indicating a timeof transmission of a previous FTM message and a time of receipt of anacknowledgement message transmitted in response to receipt of theprevious FTM message, the at least one field comprising a common portionindicative of most significant portions of the time of transmission ofthe previous FTM message and the time of receipt of the acknowledgementmessage, a first fractional portion indicative of the time oftransmission of the previous FTM message and a second fractional portionindicative of the time of receipt of the acknowledgement message. 20.The non-transitory storage medium of claim 19, wherein the first portioncomprises a TSF clock state at the time of transmission of thesubsequent FTM message.
 21. The non-transitory storage medium of claim19, wherein the first and second fractional portions comprise at leastpicosecond resolution.
 22. The non-transitory storage medium of claim21, wherein the at least one field comprises at least 96 bits.
 23. Thenon-transitory storage medium of claim 19, wherein the common portioncomprises at least a portion of a state a timing synchronizationfunction (TSF) timer of the responding STA at a time of transmission ofthe initial FTM message.
 24. The non-transitory storage medium of claim19, wherein the initial FTM message comprises at least one fieldindicating a wrap around condition between transmission of the previousFTM message and receipt of the acknowledgement message.